PWM

Pulse Width Modulation. The controller switches power to the motor on and off thousands of times per second. The ratio of on-time to off-time determines how much power the motor gets. At 100% PWM, the controller is delivering everything it can. There’s nothing left.

Why riders should care

PWM percentage is the most honest indicator of how close you are to the edge. Speed is misleading - you can be at 30 km/h (19 mph) and already at high PWM if you’re going uphill, into wind, on low battery, or heavy. Apps like EUC World and WheelLog can show PWM in real time.

PWM vs speed alarms

Speed alarms are fixed thresholds. PWM reflects actual load in real conditions. A speed alarm might not fire at 35 km/h (22 mph), but if you’re at 85% PWM because of a headwind, you’re closer to overlean than the speed number suggests.

555 take

Watch PWM, not speed. Set your safety margin alarm based on PWM or safety margin percentage. Speed lies. Load doesn’t. The field weakening article explains why PWM becomes the number that matters near the top end.